Catalyst formed from faujasite of the zeolites X, (see Milton, U.S. Pat. No. 2,882,244) or Y, (see Breck, U.S. Pat. No. 3,130,007), have been formulated by exchanging the major portion of the sodium in the zeolite as formed by H or NH.sub.4 ions and also by polyvalent cations.
While the prior art relating to exchange includes exchange with a great variety of cations, the commercial catalysts employing faujasite zeolites have been largely those in which the Na is exchanged with NH.sub.4, alkaline earth cations and rare earth cations.
Cracking catalysts which are formulated with a matrix and a Y zeolite which has been exchanged with rare earth cations, usually with an additional cation such as a monovalent cation H or NH.sub.4 or with alkaline earth cations such as Mg, has also been used extensively.
The trivalent aluminum ion has also been suggested to replace Na in the faujasite zeolites. Cornelius et al, U.S. Pat. No. 3,455,842 states that they form an aluminum zeolite by direct exchange with aluminum salt solution or indirectly by first exchanging with ammonium salt solution and then exchanging with an aluminum salt solution. No information is given as to the chemical constitution of the so-called aluminum zeolite, nor is there any description of the procedure by which an aluminum zeolite which is formed by direct exchange may also be formed by the initial NH.sub.4 exchange followed by an aluminum exchange.
McDaniel et al, U.S. Pat. No. 3,374,057 produces the zeolite in an exchange with a nitrogen base by incorporating a small amount of an aluminum salt. The process does not decrease the ratio of Si atoms to the aluminum atoms as would be expected if the aluminum was in exchange position without loss of Al from the crystal structure.
Grieg, U.S. Pat. No. 3,875,290 treats an ammonium exchanged crystalline aluminum silicate with a solution of aluminum salt or zirconium or chromium salt. The patent states that the metallic element precipitates as hydrate and on calcination appears as its oxide.